Safety assessment of the process ‘PEGRA-V’, based on Starlinger IV+® technology, used to recycle post-consumer PET into food contact materials

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Safety assessment of the substance dimethyl carbonate for use in food contact materials

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Safety assessment of the process ‘Märkische Faser’, based on NGR technology, used to recycle post-consumer PET into food contact materials

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Safety assessment of the process 'Linpac', based on Linpac super clean technology, used to recycle post-consumer PET into food contact materials

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Threshold Of Toxicological Concern Approach For The Risk Assessment Of Substances Used For The Manufacture Of Plastic Food Contact Materials

The objective of this work was to investigate whether the Threshold of Toxicological Concern (TTC) approach could be applied to the evaluation of substances used to manufacture plastic food contact materials (FCM). For this purpose, a new dataset of 232 substances used in FCM, fully evaluated on the basis of oral animal studies,was compared with the original Munro dataset. The extended dataset supports the differentiation between Cramer classes I and III, as the substances with the lowest noobserved- effect-levels are in class III both for the Munro et al. and the FCM datasets. The applicability of the TTC approach was also verified substance by substance, by comparing their TTC value with their tolerable intakes calculated from their no-observed-effect-level. The TTC approach, as proposed by Munro et al. in 1996, appears to be more conservative (more protective for consumers) than the complete individual risk assessment for 96% of the 845 compounds included in the investigation. For most of the substances, functional groups known to represent causes of non-applicability of the TTC approach have been identified. These figures suggest that the TTC approach can be a useful tool for prioritization of evaluations of lists of substances for which no toxicity data are available

Selection of a WEHI-3B leukemia cell subclone resistant to inhibition by cholera toxin

The studies on the inhibitory effect exerted by Cholera Toxin (CT) on cell growth and proliferation indicate a remarkable heterogeneity of cell response suggesting that the inhibition represents the final event of many different ways or mechanisms. After CT binding, cAMP accumulation may not occur (as in L1210 leukemia cells) or, when occurring (as in SR-4987 stromal cells), may not be coupled with the antiproliferative effect of CT. In WEHI-3B cells CT binds a Gal-GalNac-GM1b receptor and the anticlonogenic effect of CT seems correlated with cAMP accumulation. To demonstrate the central role of cAMP in WEHI-3B cells, starting from the sensitive cell strain we selected and established a clone of WEHI-3B resistant to CT. This revertant clone (WEHI-3B/CT/REV) is currently cultured in the absence of CT and in the proliferation assay shows a dramatic resistance (>46,000 than the parental cells). Stimulation ofWEHI-3B/CT/REV cells by cholera toxin failed to enhance cAMP and the ganglioside-CT binding studied on Thin Layer Chromatography (TLC) blots showed that the resistant cells lost the spot correspondent to the migration of Gal-GalNac-GM1b ganglioside. Both the lines respond at the same level to the adenylate cyclase stimulation by forskolin and the incorporation of GM1a did not decrease the resistance of WEHl-3B/CT/REV. These data confirm that Gal-GalNac-GM1b is the most important functional receptor for CT in WEHI-3B cells able to transduce the signal by enhancing cAMP which in turn inhibits cell proliferation (probably by cAMP dependent protein kinase activation). Our study describes the first cell line resistant to CT originated from a susceptible parental strain and provides a new interesting cell model for studying the cAMP dependent mechanisms involved in cell growth regulation

Pancreas developing markers expressed on human mononucleated umbilical cord blood cells

Haematopoietic system represents the main source of haematopoietic stem cells and probably of multipotential adult progenitor cells and mesenchimal stem cells at first described as colony forming unit-fibroblast. Whereas there are many studies on the gene expression profile of the different precursors along their haematopoietic differentiation, few data (sometimes conflicting) have been reported about the phenotype of the cells (present in bone marrow and possibly in cord blood) able to differentiate into non-haematopoietic cells. As both postnatal bone marrow and umbilical cord blood contain nestin positive cells able to proliferate and differentiate into the main neural phenotype (neuron, astroglia and oligodendroglia) many authors considered nestin a neuroepithelial precursor marker that seems to be essential also in multipotential progenitor cells of pancreas present both in rat and in human pancreatic islets (called nestin positive islet derived progenitors). Although the importance of nestin in these cells appears to be evident, it remains yet to clarify the number and the sequential expression of the genes coding all the transcription factors essential for beta cells differentiation and therefore the conditions able to induce the expression of many important transcription factors genes such as isl-1, pax-4, pdx-1 and ngn-3. Among them pdx-1 is a gene essential for pancreas development which is able to control ngn-3 in activating the expression of other differentiation factors for endocrine cells. Here, we describe for the first time in human umbilical cord blood cells (UCB) the pattern of expression of a panel of markers (nestin, CK-8, CK-18) and transcription factors (Isl-1, Pdx-1, Pax-4, Ngn-3) considered important for beta cells differentiation. Our data demonstrate that UCB contains a cell population having a phenotype very similar to endocrine cell precursors in transition to beta cells

In vitro toxicity of clozapine, olanzapine, and quetiapine on granulocyte-macrophage progenitors (GM-CFU)

Introduction: Atypical antipsychotics may lead to agranulocytosis because of the apoptosis caused by cells binding nitrenium mols. Studies showing the direct myelotoxicity of clozapine were undertaken years ago using different assays, and thus it is difficult to compare them with those of clozapine's analogs that have been more recently reported as causing neutropenia, agranulocytosis, and thrombocytopenia. Methods: We compared the direct toxicity of clozapine, olanzapine, quetiapine, and chlorpromazine using a previously standardized GM-CFU assay validated for predicting neutropenia. Results: The results showed that all of the drugs were characterized by dose-dependent toxicity, which was greatest in the case of chlorpromazine (IC90= 10.02 +- 0.69 mg/mL), followed by olanzapine (IC90= 13.43 +- 1.23 mg/mL), clozapine (IC90= 44.71 +- 4.42 mg/mL), and quetiapine (IC90= 137.24 +- 15.36 mg/mL). Discussion: These data agree with recent clin. reports concerning the direct or mediated toxic effects of olanzapine on progenitor and committed cells (GM-CFU) and suggest that the correlation between its plasma levels and clin. effects warrants further investigation. There are no published data concerning the bone marrow pharmacokinetics of atypical antipsychotics or their possible bioactivation by the bone marrow cell compartment, but our findings suggest that they may affect hematopoiesis in different ways, such as the direct action of them or their metabolites due to bioactivation by hematopoietic cells themselves

High sensitivity of human epidermal keratinocytes (HaCaT) to topoisomerase inhibitors

In the panorama of the numerous established cell lines, the human keratinocyte line HaCaT has a very interesting feature, having a close similarity in functional competence to normal keratinocytes. This cell line has been used in many studies as a paradigm for epidermal cells and therefore we selected HaCaT as a cell model for investigating the activity of three antitopoisomerase drugs (Camptothecin, Doxorubicin, Ciprofloxacin) on in vitro cell growth. The effect was evaluated both by a 24-h cytotoxicity test and by a 7-day antiproliferation assay, in which the cell viability was assessed by an MTT (3-(4,5-dimethyl-2-thiazolyl) 2,5-diphenil-2-H-tetrazolium bromide) test. DNA topoisomerase I was also partially purified from a nuclear extract of HaCaT cells, the level of topo I catalytic activity was measured by a pBR322 DNA relaxation assay and then the in vitro effect of antitopoisomerase drugs on the target enzyme was also assessed. The results indicated that the in vitro sensitivity of human epidermal HaCaT cells to antitopoisomerase drugs is comparable to that of many human tumour cell lines. HaCaT cells express a high level of topoisomerase I activity that is significantly inhibited by both Camptothecin and Doxorubicin and to a minor degree by Ciprofloxacin. A high correlation between the cell sensitivity to the antitopoisomerase I drug measured by the MTT test and the in vitro direct inhibition of HaCaT topoisomerase I was observed, suggesting that HaCaT cells can represent a very interesting model both for studying cellular pharmacokinetics of antineoplastic drugs on keratinocytes and for predicting possible secondary effects, exerted by these drugs on cutaneous cells, during treatment with chemotherapy